Give each compressed lesson rule an example #2135

Part of #2124.

Some rules distil an incident into one sentence and lose its trigger. An agent has to reconstruct the case before it can apply them. core/quality.md:333-336 shows the fix: a two-line example under the rule.

• core/quality.md:59-61 a flag that selects how many rules apply
• core/quality.md:92-100 variadic overrides and the frozen-checker contract test
• core/quality.md:377-378 a governance signal wired as a build gate
• core/quality-gates.md:292-310 retiring a freeze, callees before callers
• core/review.md:80-81 a closed classification in acceptance criteria

Done when

• Each listed rule has an example of three lines or fewer